/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.nutch.util.domain;

import java.io.IOException;
import java.io.InputStream;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.util.StringUtils;
import org.apache.nutch.util.domain.DomainSuffix.Status;
import org.apache.nutch.util.domain.TopLevelDomain.Type;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * For parsing xml files containing domain suffix definitions. Parsed xml files
 * should validate against <code>domain-suffixes.xsd</code>
 * 
 * @author Enis Soztutar &lt;enis.soz.nutch@gmail.com&gt;
 */
class DomainSuffixesReader {

	private static final Logger LOG = LoggerFactory
			.getLogger(DomainSuffixesReader.class);

	void read(DomainSuffixes tldEntries, InputStream input) throws IOException {
		try {

			DocumentBuilderFactory factory = DocumentBuilderFactory
					.newInstance();
			factory.setIgnoringComments(true);
			DocumentBuilder builder = factory.newDocumentBuilder();
			Document document = builder.parse(new InputSource(input));

			Element root = document.getDocumentElement();

			if (root != null && root.getTagName().equals("domains")) {

				Element tlds = (Element) root.getElementsByTagName("tlds")
						.item(0);
				Element suffixes = (Element) root
						.getElementsByTagName("suffixes").item(0);

				// read tlds
				readITLDs(tldEntries,
						(Element) tlds.getElementsByTagName("itlds").item(0));
				readGTLDs(tldEntries,
						(Element) tlds.getElementsByTagName("gtlds").item(0));
				readCCTLDs(tldEntries,
						(Element) tlds.getElementsByTagName("cctlds").item(0));

				readSuffixes(tldEntries, suffixes);
			} else {
				throw new IOException("xml file is not valid");
			}
		} catch (ParserConfigurationException ex) {
			LOG.warn(StringUtils.stringifyException(ex));
			throw new IOException(ex.getMessage());
		} catch (SAXException ex) {
			LOG.warn(StringUtils.stringifyException(ex));
			throw new IOException(ex.getMessage());
		}
	}

	void readITLDs(DomainSuffixes tldEntries, Element el) {
		NodeList children = el.getElementsByTagName("tld");
		for (int i = 0; i < children.getLength(); i++) {
			tldEntries.addDomainSuffix(
					readGTLD((Element) children.item(i), Type.INFRASTRUCTURE));
		}
	}

	void readGTLDs(DomainSuffixes tldEntries, Element el) {
		NodeList children = el.getElementsByTagName("tld");
		for (int i = 0; i < children.getLength(); i++) {
			tldEntries.addDomainSuffix(
					readGTLD((Element) children.item(i), Type.GENERIC));
		}
	}

	void readCCTLDs(DomainSuffixes tldEntries, Element el) throws IOException {
		NodeList children = el.getElementsByTagName("tld");
		for (int i = 0; i < children.getLength(); i++) {
			tldEntries.addDomainSuffix(readCCTLD((Element) children.item(i)));
		}
	}

	TopLevelDomain readGTLD(Element el, Type type) {
		String domain = el.getAttribute("domain");
		Status status = readStatus(el);
		float boost = readBoost(el);
		return new TopLevelDomain(domain, type, status, boost);
	}

	TopLevelDomain readCCTLD(Element el) throws IOException {
		String domain = el.getAttribute("domain");
		Status status = readStatus(el);
		float boost = readBoost(el);
		String countryName = readCountryName(el);
		return new TopLevelDomain(domain, status, boost, countryName);
	}

	/** read optional field status */
	Status readStatus(Element el) {
		NodeList list = el.getElementsByTagName("status");
		if (list == null || list.getLength() == 0)
			return DomainSuffix.DEFAULT_STATUS;
		return Status.valueOf(list.item(0).getFirstChild().getNodeValue());
	}

	/** read optional field boost */
	float readBoost(Element el) {
		NodeList list = el.getElementsByTagName("boost");
		if (list == null || list.getLength() == 0)
			return DomainSuffix.DEFAULT_BOOST;
		return Float.parseFloat(list.item(0).getFirstChild().getNodeValue());
	}

	/**
	 * read field countryname
	 */
	String readCountryName(Element el) throws IOException {
		NodeList list = el.getElementsByTagName("country");
		if (list == null || list.getLength() == 0)
			throw new IOException("Country name should be given");
		return list.item(0).getNodeValue();
	}

	void readSuffixes(DomainSuffixes tldEntries, Element el) {
		NodeList children = el.getElementsByTagName("suffix");
		for (int i = 0; i < children.getLength(); i++) {
			tldEntries.addDomainSuffix(readSuffix((Element) children.item(i)));
		}
	}

	DomainSuffix readSuffix(Element el) {
		String domain = el.getAttribute("domain");
		Status status = readStatus(el);
		float boost = readBoost(el);
		return new DomainSuffix(domain, status, boost);
	}

}
